This invention relates to the art of flexible metal hose and more particularly to a method of preparing a flexible metal hose and securing a connector or fitting thereto, as well as the assembly obtained thereby. The invention is particularly applicable to flexible metal hose that is comprised of an inner corrugated tube which is covered by a sheath of braided metal wire. Any one of a number of fluid fittings may be secured to ends of the flexible metal hose, and it is envisioned that opposite ends of the flexible metal hose may even incorporate different types of fittings. The assembly finds application in installing flexible loops that allow for thermal expansion, misalignment, intermittent flexing, or continuous flexure, for example as may be caused by vibration. Of course, and as will be readily understood, it may also be used for static bend arrangements. These uses and the environment are merely exemplary, and it will be appreciated that the invention may be advantageously employed in still other environments and applications.
A conventional, prior art method of assembling a flexible metal hose connector incorporates two separate welding operations. As used herein the term "welding" is to be accorded its broadest interpretation and encompasses various types of welding as well as the concepts of brazing and soldering. An alternate expression for welding is fusion bonding and these terms will generally be used synonymously.
According to one prior art method of assembling flexible metal hose, the corrugated tube and the braided sheath are terminated at a desired location. A sleeve is then advanced over the metal braid and aligned with the terminal ends of the tube and braid. A first weld, known as a cap weld, joins the sleeve, braid, and tube together. Thereafter, a fitting is advanced into abutting engagement with the first weld area, and a second weld, particularly a fillet weld, joins the external periphery of the fitting to the terminal end of the metal hose, i.e., the welded sleeve, braid, and tube.
Although this method of assembly has been used with a tremendous amount of commercial success, a primary drawback is that it relies on the skill of the individual welder. Variations may occur from one metal hose connector to another, whether assembled by the same or different welders. For example, the welder secures the tube, braid, and sleeve together in the first weld step. These three components may not be concentrically secured together, or one of the components may not be effectively secured to the other two components. The welder must also provide a generally planar surface to adapt the intermediate assembly to receipt of the fitting. Again, such steps are labor intensive and subject to variation from one completed flexible metal hose connector to another.
A number of other methods have been proposed in prior art patents. These include U.S. Pat. Nos. 2,172,532--Fentress; 2,473,879--Guarnaschelli; 4,527,819--Desilets, et al.; 3,740,832--Toepper; 2,028,600--Guarnaschelli; 2,444,988--Guarnaschelli; and 2,300,547--Guarnaschelli. The subject invention, though, is believed to offer a number of advantages over these prior art arrangements.